Scientists have been trying to perfect techniques for collecting data regarding rock movement, such as that which is caused by the flow of water in a river or stream, which is necessary for a thorough study of erosion, flooding, sedimentation and the like. One technique that scientists have employed involves collecting rocks from the site under investigation and implanting a small magnet inside each rock. The rocks are then placed strategically upstream of their anticipated path of travel. After an event of flooding, the new positions of the rocks are traced by detecting the magnet field of the magnets inside each rock. The movement which the rocks have undergone can then be deduced from the changes in the positions of the rocks. One disadvantage of this method is that it is costly to collect rocks, implant a magnet in each rock, strategically place the rocks back at the site under investigation and detect the rocks having magnetic implants after the event. Another disadvantage of this method is that, in adding magnets to the rocks and placing the rocks back into the environment, there is a human intervention that can skew the data received.
A proportion of rocks at any site under investigation have a naturally occurring remnant magnetization that is strong enough to be detected. The signal level which can be obtained using existing technology for detecting the remnant magnetization in a rock that is capable of being detected is approximately 10 microvolts. By working out a statistical average of the percentage of rocks at a site under investigation that are capable of being detected, rough estimates can be made as to the real number of rocks being moved. This method of detection of rock movement requires a considerable amount of study to arrive at a statistical average as to the percentage of rocks at the site under investigation having a remnant magnetism of sufficient strength to generate a signal of magnitude of 10 millivolts. It also requires the use of expensive amplifiers to condition the signals.